Include stdbool.h for c-api

the c-api needs stdbool included

Author: HeatXD

GekkoLib/include/gekkonet.h

@@ -26,6 +26,8 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 #pragma once
 
+#include <stdbool.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif